Sequencing control apparatus



April 12, 1949. A. v. SAMPSEL SEQUENCING CONTROL APPARATUS 4 Sheets-Sheet 1 Original Filed Dec. 7 1942 2 y .P u m A. v. sAMPsEL 2,466,914

SEQUENCING CONTROL APPARATUS 4 Sheets-Sheet 2 kwfw? April 12, 1949.

Original Filed Dec. 7, 1942 A ril 12, 1949. A. v. SAMPSEL 2,466,914

SEQUENGING CONTROL APPARATUS Original Filed Deb. 7, 1942 4 Sheets-Sheet 3 fnz/erzzr P 1949- A. v. SAMPSEL 2,466,914

SEQUENCING CONTROL APPARATUS Original Filed Dec. 7, 1942 4 SheetsSheet 4 l lgimmum Patented Apr. 12, 1949 SEQUENCING CONTROL APPARATUS Arthur V. Sampsel, Spring Valley, 11]., assignor to. Sears,- Roebuck'and co flliieago', 111., a corporation of New York Division of abandoned application serial No. 488,069, December 7, 1942. This application January 10; 1947, Serial No. 721,322

(01. ZOO-38) 8 Claims.

1 This application is a continuation in part'of U. S. PatentNo. 2,304,124: and isadiv-ision of pending application, Serial Number 468,069 filed" December 7, 19421'01' Temperature c'ontrol and' vide fire control mechanism adjustable to feed a furnace from a fraction of aminute, more or less, to seven minutes, more or less, at one, twoorfour, or at other, intervals per hour. or'other units. of time.

An. additional object is to provide a device: for rendering the fuel feeding means intermittently operative during a continuous heat demand by the room thermostat, said device'constructed so as to be adjustable to various positions in. which the same is inoperative or operative at different periods and frequencies.

An additional object'involves the provision of a control device adapted to cause intermittent fuel feed to keep the fire alive'a-nd also adapted to causeintermittent fuel feed during continuous heat demand by a room thermostat, the device being adjustable for various periods and frequencies.

Further objects and advantages. of my invention will appear as the description proceeds.

The invention will be. understood upon reference to-the following description and theaccompanying drawings, in which:

Fig. 1 is a fragmentary vertical sectional diagrammatic view through a building, in which is installed a damper-responsive control system embodying features of my. invention.

Fig. 2 is a detailed wiring diagram of. thesystem appearing in Fig. 1.

Fig. 3 is a fragmentary diagrammatic view showing how a portion of the wiring of. Fig. 2 may be modified to adapt the system to an-installation which is not damper-controlled; as well asto one which is damper-controlled.

Fig. 4 is a fragmentary elevationof a firecontrol clock switch and associated cam mechanism embodying features of my invention.

Fig. 5 is a fragmentary sectional view taken as indicated by the line 5-5-in Fig. 4, showing, the switch open.

Fig. 6 is a fragmentary sectional view taken as indicated by the line 6-6 in Fig. 4',-but'withthe parts adjusted so that the switch is closed.

Fig. 7 is a fragmentary plan-view tak'enas indicated by the line 'I'i in-Fig. 5.

Fig. 8 isaav fragmentary sectional-.view-take'n as indicated-by theline'ika farms.

Fig. 9-isa fragmentary elevation of a combined fire pilot and thermostat interrupting control embodying features of my invention.

Fig. 10 is a fragmentary sectional view taken asindicated by the line ill-l0 in Fig. 9, showing one of the switches open and the other closed.

Fig. 11 is a fragmentary sectional view taken as indicated by the line H---l l: in Fig. 9, but with the parts in a different adjustment.

Fig. 12 is a fragmentary plan view taken as indicated by the line l2-l2 in Fig. 10.

Fig. 13 is a fragmentary sectional view taken as indicatedby theline l3-l 3 in Fig. 10.

Fig. 1411s a diagram showing how the form of theinvention appearing in Figs. 9 to 13 may be employed.

Fig. 15 is a fragmentary sectional view taken as indicated by the line I 5--|'5 in Fig. 9.

In the drawings, the numeral Id represents a floor of a building, separating the basement 12 from the. living or other quarters, which may be divided by walls such as the wall l3 into enclosures or zones l5a and I512.

In the basement [2 there is provided a coal bin 18 and a furnace F, which may be of the hot air type, as shown, and adapted for coal burning. An underfeed stoker 21 comprising a screw conveyor 22 extends from the bin to the furnace. A suitable motive'means S is provided for operating theconveyor for feeding coal from the bin to the furnace, and a blower or fan 21 is also provided, operated by a motor B.

For illustrative purposes only, I have elected to show and describe a furnace of the hot air type,

' surrounded by a casing or bonnet 30 communicating through a plenum chamber 3| with air dues or ducts 33a and 33b, whereby warm air in the winter and cool air in the summer, when the furnace is not used, is conveyed to the respective zones or rooms whose temperatures are to be controlled.

Each zone has a thermostat Ta, Tb controlling a damper-control mechanism Da, Db, which in turn operates, in addition to a damper or valve for controlling flow of heat exchange medium to the respective zones, a switch controlling the stoker motor S and the blower or pump motor B throughconnectionsand apparatus which may be suitably mounted on a master panel as indicated generally at M. The panel apparatus appears in detail diagrammatically in Fig. 2 and elsewhere.

The winter operation of the apparatus of my invention is substantially as follows: When any zone thermostat calls for heat, the appropriate damper will be opened and cause the stoker S and the blower B to be placed inv operation. If thereafter, and before said thermostat has demanded ashutoif, a thermostat in another zonecalls for heat, the appropriate damper for such otherzon'e will be opened. However, since the stoker and blower are already in operation no alteration in the performance of these elements will occur. This procedure, of course, will be the same for any number of zones, the demand for heat in any additional zone resulting merely in the opening of the appropriate damper while the stoker and blower continue to operate, so long as at least one thermostat calls for heat. As long as.

at least one thermostat demands heat, the electrical circuits controlling the stoker and blower will be closed and, therefore, the demand by any other thermostat that heat be shut off will result merely in the closing of the damper corresponding to such other thermostat without affecting the stoker or blower.

, In other words, under normal conditions, the stoker and blower will not shut down until all of the thermostats have ordered a discontinuance of heat.

A time fire pilot control is provided to operate the stoker at suitable intervals in mild winter weather to keep the fire from going out.

The above zone and time controls are subject to the following exception, however. In the event that the furnace becomes heated above a predetermined temperature, the electric circuit controlling the stoker will open and will remain open at least as long as said temperature is exceeded. While the operation of the stoker is thus arrested, the furnace temperature may continue to increase, due to fire acceleration or heat from a stimulated fire, for example. In compliance with ordinances, municipal codes, underwriters requirements and the like, provision may be made for the automatic operation of the blower when a predetermined higher furnace temperature obtains.

To adjust the apparatus for summer operation it is necessary merely to operate a few switches, the effect of which is to disable the stoker and condition the dampers whereupon the blower may supply cool basement or other air to the individual zones as required by the respective zone thermostats. By restoring the original adjustment of the switches, the apparatus is prepared for winter operation.

By a simple expedient, which will appear, the apparatus on the master panel may be adapted for operation with or without damper control, as desired.

The stoker circuit as it is influenced by the zones will be described first. In the stoker operating circuit there is provided a suitable switch 50, Fig. 2 which may be closed during the winter and open during the summer, so that the stoker operates only during the winter. In the same circuit there is provided also a safety or limit control thermostat switch 5| which is adapted to open and thereby stop the stoker when the furnace reaches a predetermined high temperature. A conductor 53 connects the switch 5| to one side of the line voltage 54. From the other side of the line voltage a wire 58 is connected to the blade 58 of a relay 59, said blade being urged away from the relay contact 6| by a spring 62. The contact BI is connected by a wire 63 to the motor of stoker S, thereby completing the zone-controlled stoker circuit. With winter conditions prevailing, so that the switch 50 is closed, and with the safety switch 5| closed, i. e., when the furnace is not above a predetermined temperature, the operation of the stoker in this circuit is dependent on the closing of the switch of the relay 59.

The winding 86 of the relay 59 is connected by a wire 81 to the low voltage side 68 of a transformer I0 connected to the line 54. A wire 1| connects the other end of the transformer side 88 to a post I2, and a wire 13 extends from the post to the blade I5 of a switch 16 associated with each zone. Each switch I6 has a contact 11. The blade is urged by a spring I8 away from the associated contact 11. Each switch I6 is controlled by a room thermostat, as will be explained in detail. A wire connects each contact 11 to a second post 8|, and a wire 82 completes the relay circuit to the relay coil 66.

It is apparent that the switches I8 are connected in parallel, so that when at least one is closed, i. e., when any zone or room demands heat in the winter, the relay coil 68 is energized, causing the blade 58 to engage the contact BI and thereby close the stoker circuit for operating the stoker, and, as will appear, the blower.

There is likely to be a period from time to time during which the stoker will not be operated by heat demand, as when mild winter weather prevails, and accordingly the fire in the furnace might die. I provide a fire control mechanism for such a contingency. To that end there is provided a synchronous clock 85 which is connected through a manual or other suitable switch 86, closed only in winter, and a wire 81 to one side of the line 54, and by a wire 88 to the other side of the line. Cam mechanism indicated schematically at 90, hereinafter more specifically described, operated by the clock 85, periodically enables the blade 9| of a switch 92 to move into engagement with the contact 93 to close said switch, the blade being urged by a spring 95 away from the contact. A wire connects the contact 93 to the coil 99 of a relay I00, and this coil is connected by a wire IOI to an end of the low voltage side 68 of the transformer I0, the other end being connected by the wire II to the blade 9|, completing the clock-controlled relay circuit.

It will be observed that the wire 63, connected to the stoker S, is connected to another wire I03 which is connected to the blade I04 of the relay I00, said blade being urged by a, spring I05 away from a contact I06 of said relay. A wire I08 connects the contact I06 to that side of the line to which the blade 58 of the zone thermostat-controlled relay 59 is connected. Thus the relay 59 is by-passed when the clock periodically energizes the other relay coil 99, drawing the blade I04 into engagement with the contact I06. The clock may operate the stoker any desired number of times per hour, for example, for any desired duration each time; from, say, fifteen seconds, more or less, to, say, seven minutes, more or less.

The stoker will be operated when either or both of the relay coils 59 and 99 are energized, i. e., when either one or more zones and/or the clock calls for heat, provided of course the stoker safety switch 5| is closed.

The blower B is operative in the winter to deliver warm air and in the summer to deliver cool air. It may be connected by a wire I|0 to the blade I of a limit control switch II2 which is preferably of the thermostat type and is adjusted to open during winter if temperature of the air in the furnace bonnet is too cool. The contact I I3, engageable by the blade I I when the bonnet air is warm, is connected by a wire I I5 to o, side of the line 54. A second wire II! is extended from the blower B and is connected to a back contact I I8 on the relay I00. The relay blade I04 is urged 5' by the spring I05 into engagement with the back contact H8, completing a blower circuit through the wire I03, relay switch contact 6| and associated blade 58, and wire 56 to the other side of the line 54.

It has been seen that the zone-controlled relay 59. may operate to run the stoker S. It is now apparent that, said relay'at the same time may cause operationof. the blower B, provided that the air in the furnace bonnet .is suificiently warm to close the air limit switch H2 and further that the clock does notcausethe relay I to withdraw the blade I04 from the contact '8. Tests have shown,- that periodic stopping of the blower by the clock has a negligible efl'ect on the temperature of the zones. It willbe appreciated that even while the blower is idle the warmair will pass such dampers as may be open and into the, heat-demanding zones, by natural draft.

It has been pointed out that the switch 5I will be open and stop the stoker at a predetermined maximum furnace or bonnet temperature. The heat from the fuel in the furnace may raise the temperature of the furnace substantially above that at which the switch 5I opens. The furnace nevertheless may have a safe operating temperature range above said predetermined temperature. To prevent overheating, I provide a blower limit or emergency switch I 22 which is normally open butis designed to close at the upper limit of said range and to maintain the blower in operation regardless of lack of zone demand and of the clock, to dissipate the heat accumulation in the bonnet until the furnace is cooled to a temperature preferably intermediate the limits of said range, whereupon the switch I22 may open. Zone operation of the blower is not affected by the switch I22, but only by the clock. The switch I22. isconnected by a wire I23 to the line 54 and by a wire I24 to the wire I I1, thereby by-passing the relay switches containing the blades 58 and I04, respectively, and closing a circuit controlling the, blower. In a short time, say about one minute, more or. less, the blower will discharge suificient air to effect the desiredamount of cooling and thereby open the switch I22. In the. event the dampers are closed during suchemergency operation of the blower, the-air thus blown will pass by way of the usual clearance between the dampers and the duct walls. Or, such air may discharge through a back pressure by-pass (not shown) to the-outside of the bonnet.

In a hot air installation atemperature range or difierential of about 100 F. has been found satisfactory, although it is to beunderstood that the switches 5] and I22 may be adjusted or formed to operate at any temperatures desired or required. For example, the switch 5| may open at a bonnet temperature of 300 F. and the auxiliary switch I22 may close at 400 F. and open at 375 F. When hot water is used, it is desirable to operate e S t SI and I22.at the same time, a circulating pump being of course used in lieu of a blower. When steam is used,v emergency means such as a blow-off valve may be employed so that the switch I22 may be dispensed with.

The operation of the stoker below the stoker cutoff temperature andv of the blower below the blower cutoif temperature is dependent on. the controls already described.

During warm weather it isdesirable to operate the .blower to furnish cool air from the bonnet to the various zones, the furnace being of course unheated; Since the low. limit air control switch. II 2-; for the, blower will be open at such time, I provide a manual or other suitable switch I which is maintained open in the winter; so as not to overcome the effect of'the opening of the switch II'2, but is closed in the summer.- At such time the blower limit switch I22 is of course open and the clock idle. The clock switch 92 should be open so that the blade I04will be engaged with the contact II8. If, when the clock switch 86 is opened for summer operation of the apparatus, the switch 92 happens to be closed, the cam mech-- anism 90 may be adjusted to open said switch, as will appear. Theblower circuit is therefore open and closed only when any one or more of the zone thermostat controlled switches 16 closes, as has been pointed out.

I provide a simple yet unique control for the damper and switch 16 associated with-each zone. This control includes a damper motor I35 operatively connected, through any suitable means, such as reduction gearing (not shown), with a crank arm I36 (Fig. 1) from which a connecting rod I31 extends to a crank arm I39 on a damper valve I40, the arrangement being such that in one stroke of the arm I36 the valve will open fully and in the return stroke the valve will close fully. The damper motor I35 also turns a cam I43 adapted to close the switch 16' by moving the spreader 15 against the action of the spring 18 and into engagement with the contact 11, and also adapted to start and stop the motor, as will appear.

The damper motor I35 is connected to the line 54 and is controlled by a switch I41 having a blade I48 urged away from the contact I49 by a spring I50. This blade is adapted to be moved into engagement with the contact I49 when a relay coil I53 is energized. This coil is connected to the low voltage side I54 of a transformer I55, fed by theline 54. The coil I53 is'connectedto the blade I51 of a single pole double throw switch I58, a spring I59 urging the blade into engagement with a contact I6I and the cam I43 being operative when moving the blade 15 of the switch 16 to also move the blade I 51, against the action of the spring I59, into engagement with the contact I62. These contacts lead respectively to winter poles I and IE6 at one side, and to summer poles I68 and I69 at the other side, of a double pole double throw switch I10, said switch comprising an arm I1I having blades I13 and I14 engageable with the first pair of poles I66 and I65 in the winter and with the second pair of poles I68 and I69 in the summer. The switch bladesv I13 and I14 are connected respectively with the contacts I16 and I11. of a single pole double throw thermostat I18, the movable blade I 19 of which is connected to the low voltage side I54 of the transformer I55, completing various circuits including the relay coil I53. The blade I19 isadaptedto engage the contact I16 when heat is not demanded inthe winter and when cooling is demanded in the summer, and'to engage the contact I11 when heat is demanded in the winter and when cooling is not demanded in the summer.

The operation of the damper, control will now be described, first for winter conditions and then for summer conditions.

In the winter, the blades I'I3and I14 are engaged with the poles I66 and I65, respectively. Let it be assumed that the zone. under consideration is not demanding heat. At such time the thermostat blade I19 is engaged with the contact I16, and. the damper is closed, thev spreader cam I43 being. in its inoperativeposition so that the switch 16, is held open by the spring 19 and the, blade I51 is engaged with the contact I6I'. The

cam should not be turning under such conditions because if it were it would cause the switch 16 to close and cause the stoker and blower to operate when heat is not wanted in the zone. It will presently appear that with the circuit arrangement referred to the cam under such conditions remains in an inoperative position.

Under the conditions just stated, in order for the cam I43 to be idle, the switch I41, controlling the damper motor I35, which runs the cam, must be open and hence the relay coil I53, controlling the switch I41, must not be energized. This coil is in a circuit which includes the blade I51 and contact I6I, contact I 65, blade I14 and thermostat contact I11, but since the contact I11 is not engaged with the blade I19, the coil circuit is open, so that the switch I41 is open and hence the damper motor I35 and cam I43 are idle.

Now let it be assumed that the zone requires heat. The thermostat blade will snap into engagement with the contact I11, so that, following through the relay coil circuit from that point in the next previous paragraph, the circuit continues from the contact I 11 through the blade I19 and low voltage side I54 of the transformer I55 back to the coil I53 and hence the circuit is closed. The coil accordingly closes the switch I41, starting the damper motor I35 and cam I43. The damper motor opens the damper while the cam closes the switch 16 and disengages the blade I51 from the contact I6I. As will be seen, this disengagement opens the relay coil circuit and hence the damper motor switch I41 opens, stopping the damper motor. The parts are so arranged that this disengagement occurs just at or after the closing of the switch 16, so that the opening of the damper will be completed and the cam will stop at a position where it maintains the switch 16 closed against the action of the spring 18 and maintains the blade I51 in engagement with the contact I62 against the action of the spring I59.

With the thermostat blade I19 engaged with the contact I11 and the blade I51 engaged with the contact I62, the relay coil circuit extends from the coil I53 through the blade I51, contact I62, contact I66, blade I13 to thermostat contact I16 which is free of the thermostat blade I19, so that the relay coil circuit is open, Q. E. D.

The switch 16 being now closed, the stoker control relay coil 66 is energized and the relay switch blade 58 moved into engagement with the contact 6|, starting the stoker S. The warm air limit switch II2 will be closed if the air in the bonnet is sufficiently warm, as it is likely to be. In any event, the furnace will heat the air quickly, so that this switch will close in a minute or two and thus operate the blower.

As has been pointed out, under normal conditions, when the pilot fire control, i. e., the clock, operates the stoker S, the blower does not operate, and this condition is naturally desirable when no heat is needed. If the zone at such time should be demanding heat its damper will be open so that there will be some delivery of warm air by natural draft. In cold weather the clock adjustment is preferably such as to operate the stoker sparingly inasmuch as the zones will make adequate demands on the stoker to keep the fire from dying. Consequently the stoppages of the blower by the clock will be of such short duration as not to appreciably affect the comfort in the zones. When the weather is relatively mild the clock adjustment preferably will be such as to operate the stoker more often or for longer periods because of the corresponding paucity of the zone demand for stoker operation, and at such times it is accordingly desirable that the blower be idle, the dampers being closed.

The delivery of warm air will be continued until the switch 16 opens, and, as will be explained, this will occur when the thermostat I18 stops calling for heat, for then the thermostat blade I19 will separate from the contact I11 and become engaged with the contact I16.

It will be recalled that the damper motor I35 and the cam I43 stopped with the switch I41 open, the damper open and the cam holding the switch 16 closed and the blade I51 free of the contact I6I and in engagement with the contact I62, and because the thermostat blade I19 was separated from the contact I16, the circuit of the relay coil I53 was open. Now, however, that the thermostat blade I19 has become engaged with the contact I16, the circuit of the relay coil I53 is closed since it runs from said coil through the blade I51, contact I62, contact I66, blade I13, thermostat contact I16, thermostat blade I19, low voltage side I54 of the transformer I55 and back to the coil I53. Accordingly, when the thermostat blade I19 engages the contact I16 and the coil I53 is energized, closing the damper motor switch I41 against the action of the spring I50, starting the damper motor I35 and cam I43. The cam turns, allowing the spring 18 to open the switch 16 and thereafter the spring I59 to withdraw the blade I51 from the contact I62, thereby opening the coil circuit so as to deenergize the coil I53 and allow the spring I50 to open the damper motor switch I41. When the damper motor stops, the damper is closed and the cam is in inoperative position, and since the switch 16 is now open, the stoker control relay coil 66 is deenergized and the relay switch 58 is open, so that the stoker and blower are both stopped. Now the conditions are the same as at the beginning of the cycle of operation just explained.

Thus it is clear that in the winter heat will be supplied to any zone demanding it, regardless whether any other zone is demanding it, and that heat will not be supplied to any zone not demanding it; that provision is made against the delivery of air unless it is of the desired minimum temperature; that the fire will not go out even though heat may not be demanded for a long period; that the stoker will stop when the furnace temperature exceeds a predetermined high temperature, the furnace being allowed to be heated by the fuel therein to a higher temperature limit, as when hot air is the heat exchange medium; that at such upper limit the blower will be turned regardless of lack oi. zone demand for heat, to preclude overheating of the furnace and will cool the furnace to a safe temperature before being turned off that the blower will supply heat substantially whenever demanded, and the clock cannot operate the stoker nor prevent operation of the blower while the furnace is within a predetermined temperature range. When hot water is the medium, emergency cooling of the furnace starts immediately upon stopping of the stoker at a predetermined high temperature. When steam is the medium, emergency operation of a blow-off valve will take care of the situation.

In the summer, the switch 50, controlling the stoker S, is thrown and maintained open, so that the stoker and hence the furnace are not in operation. The stoker limit switch 5I is closed but of course ineffectual, and the blower limit switch I22 is open. The clock switch 86 is open so that the clock is stopped. The switch I30, however, is closed, and since it is in parallel with the air limit switch II2, it is immaterial whether the latter is open or closed. Now it will be observed that there is a blower circuit extending from the blower through the switch I30- to one side of the line 54, from the other side of the line to the relay switch blade 58, associated contact 6|, wire I03, blade I04, held engaged with contact I I8 by spring I05, and wire I I1 back to the blower. Thus the closing of this circuit is dependent upon the positions of the blades 58 and I04. The blade I04 is moved from the contact II8 when the coil 99 is energized. To preclude such energization the clock-operated cam mechanism 90 is adjusted when the clock is stopped, so as to open the switch 92 controlling said coil. Accordingly in the summer the blower circuit is dependent on only the switch blade 58, which is controlled by the relay coil 66 which is controlled by any zone switch 16. This switch is closed when the zone associated therewith needs cooling and is open when cooling is not demanded, as will appear.

Upon the arrival of summer the stoker and blower will not be called upon at all for the supply of heat. When there is no demand for heat, it has been seen that the thermostat blade I19 is engaged with the contact I16, the damper motor I 35 is stopped with the damper closed, and the switch I41 accordingly open and the cam I 43 in inoperative position so that the switch 16 is open and the blade I51 engaged with the contact I 6|, winter-summer switch handle I 1| being of course in its winter position, with its blades I13 and I14 respectively engaged with the contacts I66 and I65.

With this arrangement prevailing, no closing of the switch 16 can occur unless heat is demanded. It is desirable to furnish the zones with cool air during the summer, and that is made possible by the system I have provided, merely by throwing the switch handle "I to its summer position, when the blades I13 and I14 respectively engage the poles I68 and I69. For the purpose of explaining a cycle of summer operation, let it be assumed that, when the switch handle "I is thrown as just noted, the zones are comfortably cool so that none is demanding to be cooled. As the operation of all zones is the same, it will suifice if reference is made to but one zone.

It has been pointed out that in the summer the thermostat blade I 19 is engaged with the contact I16 when cooling is demanded and with the contact I 11 when cooling is not demanded. With the blade I19 engaged with the contact I11, the circuit of the relay coil I 53 extends from one side of said coil through the blade I51, contact I6I, pole I65, pole I68 and blade I13 to contact I16, which is free, so that the circuit is open and hence the coil is not energized, the switch I41 is open, the damper motor I35 and cam I43 are idle, the damper remains closed, the blade I51 continues engaged with the contact I6I and the switch 16 remains open so that the blower B is not in operation.

When the zone demands cooling, the thermostat blade I19 leaves the contact I11 and engages the contact I16, so that the above-referred to relay circuit continues from the contact I18, through the blade I19, low voltage side I 54 of the transformer I55 and back through the coil I53, closing its circuit. The coil thus energized closes'the damper motor switch I41 against the action of the spring I50, closing the damper motor circuit so that said motor and the cam I43 commence turning, the motor opening the damper and the cam operating to close the switch 16 and then to separate the blade I51 from the contact I6I, breaking the circuit of the relay coil I53, allowing the spring I50 to open the damper motor switch I41, stopping the motor with the switch 16 closed and the blade I51 engaged with the contact I62. Closing of the switch 16 closes the circuit of the relay coil 66 which, thus energized, draws the blade 58 into engagement with the contact 6|, closing the blower circuit. The blower B operates, supplying the cool air in the bonnet to the zone.

When the zone has cooled sufliciently, the thermostat blade I19 leaves the contact I16 and engages the contact I11. Then the circuit of the relay coil I53 is closed, the current flowing from the coil through the blade I51, contact I62, pole I66, pole I69, blade I14, thermostat contact I11, thermostat blade I19, low voltage side I54 of the transformer I55, back to the coil I53. Thereupon the coil I53 is energized, closing the damper motor switch I41 against the action of the spring I50, starting the damper motor I35 and cam I43, the motor turning the damper toward closed position and the cam allowing the spring 18 to open the switch 16, stopping the blower B, and allowing the spring I59 to move the blade I51 away from the contact I62, thereby deenergizing the coil I53 so as to permit the spring I 50 to open the switch I41, stopping the motor I35 with the damper closed and the cam in inoperative position. This completes the cycle of summer operation, and it will be observed that the blower will operate and deliver cool air as long as any one or more zones demand it, and only to the zone or zones demanding it.

When winter comes, the switch handle IN is moved to its winter position, where its blades I13 and I14 respectively engage the poles I66 and I65, the stoker controlling switch 50 is closed, the clock controlling switch 86 is closed and the switch I30 is opened. The winter cycle has already been explained.

It will be appreciated that if the heating medium be water or any other substance the member B could be a pump and there would be a water jacket, for example, instead of a bonnet, pipes instead of ducts, and radiators or unit heaters in the respective zones, as will be appreciated by those skilled in the art.

In Fig. 3 I have shown at M a unit like the unit M but having an additional binding post I and a single pole double throw switch I81 whose blade I90 is operative through contacts I9I and I92 to connect the posts 8| and I85 alternatively to the relay coil 66. The unit M, above described in detail, employing only the posts 12 and 8|, is used when the stoker and blower are controlled by the damper motors associated with the various zones, so that only one thermostat per zone is necessary. The unit M, however, is adapted for an installation where the stoker and blower are independent of the damper motor, as well as for one in which the stoker and blower are damper'motor controlled. In the former type of installation, each zone has two thermostats, one to control the damper in a separate thermostatdamper motor circuit (not shown) and the other to control the stoker and blower independently of said circuit and through said unit M, employing said additional post I85 and said switch I81. In such case the contact I16 of each zone thera-aaetcg era I1 1 mostat is-connected to the post I85, the contact =l-"l 'l f to the post 81 iandtthethermostatz blade 1:19

to the post 12,-and'the switch blade .190, which preferably is ofthe manual itype,:is connected .in

the-summer with theconta'c't I91 andlhence with the thermostat blade 17-19 andiin the winter with thecontact I02 and-hence with 'the thermostat contact [11.

Now, when the temperature of 'a zone is too great the thermostat blade I19 engageszthe :contact 1'6, and "when heat is demanded the :bl'ade engages the contact 1 1 In the winter, the :contact H6 is disconnected from and the contact l nisconnected to the relay coil '66, -so that' the coil is energized only when-the blade enga'g'es the contact L11, to operate the stoker'and blower,

subject to'the conditions noted above relative to clock and limit control operation. In the summer,'the stokeris inoperative, so' that the coil 66 is .employed'to operate the blower, the contact I-16"being connected to and the contact 111 being disconnected from the relay coiL so that the coil is energized only when cooling is demanded. As in the 'case :of the damper motor controlled installation, it will be observed "that L the r stoker and blower controlling thermostats in the variouszones are all conne'cted in iparallel so that-as long as there is a demand for he'atin the winter or cooling in the summer, whe'th'er .ffrom'only one or from morethan one zonefthe apparatus will function to supplysuch demand, the damper thermostat in each such demanding :zone "operating to open the associated damper to conduct the blown air into suchzone.

When the unit'M' is used with damper :con-

trol, the switch blade i l 90 will he at alltimes vengaged with the contact 1'92 and the switches 16 connected to the posts 1-2 :and 8l, as :shown in Fig. 2.

The clock-operated cam mechanism for opening and closing the Stoker-controlling switch 92 "is-operated at intervals which-preferably maybe -varied as to number and duration. For exam- *stoker one, two or four times, "for anywhere'from about seconds, more or less, to :about :seven minutes, more or less, eachtime. Thus the clock may operate the stoker throughout a range of from one 1"5 second period per-hour to four seven minute periods perhour. It is to'be understood that although in the ensuing description, reference is madespecifioally to the=mechanism"m'aking possible the variations just mentioned, the

same principles may be employed to provide for clock operation of thestoker any desired fractional or integral number of times including three or above four and for any desired duration above seven minutes each time, per hour or per any other desired period.

Referring now more particularly to the embodiment of the fire pilot control unit'featured in "Figs. 4 to 8, inclusive, attention is now directe'dto the reference numeral 85, which-designates the supporting "base. A synchronous motor, not shown, is provided with appropriate reduction gearing to rotate the hour shaft 200 so that itwill make precisely one revolution every sixty minutes. 'The shaft 200, "Figs. land 5 is shouldered at 2'0! affording a reduced diameter portion designated'202 on which is supported a wan 216.

surface rcam assembly .201 between the tensioniing :tspring washer 206 and the .lock nut 240, threaded "upon a further :reduced and threaded portion :-:20.4 of shaft 200.

Thecam assembly 201 ismade-of two principal 'fparts; one'ofwhich will be referred'to as the primar-yrportion 2| I andthe other as the secondary :p'ortion 1235. The primary portion 2H is provided with anarcuate recess on its rear face :designated 215, :Fig. 8, describing approximately 1l.4.5"between.its radial defining edges 2|8 and M0 The recess 'extends'inwardly to the radius A coaxial :slot 212 "coincident with the :de'fining wall 2H5 .extendsithrough the disc connecting with the concentric circular surface recess- 209 on the front faceof the cam disc 201.

From Figs. 4 and 8 it may be observed that the vperipl'ierylof cam 201 is substantially circular, exceptifor'asshallow depression beginning with the radial definingline 2 l8 and'extending to a point -.about.ihalfzwa-y in the direction approaching the other radial'line 218. This jperipheral clearance isjprovided to-accommodate a transversely extending pointer arm 245 which is integral with a triangular plate 222 pivoted on the reduced shoulder portion 202. The'innermost extremity of plate 202 is sandwiched between the thin hub face-229 and a small cam disc 235 which is especiallyform'ed to accommodate the'innermos't extremity 230ao'f the-triangular plate 222. In this imanner'camdisc 235 is integrally associated with thegplate 222 so that the two of them move in unison during adjustment which may partake of any position within thefangle, roughly 72, as 'aiforded by the-peripheral clearance to'the point- :er arm 245 andtis also affor'ded by the radial notch 2l2stoztheiofiset portion-2250f plate .222 that extends therethrough.

Once a desired adjustment is established, the triangular, plate :222 may be'anchoredto the main "disc by drawing up the securement screw fi244fthat=extends through another'transverse slot 243 :inthe disc :20! as clearly shownin Figs. 4, 5 :andr8. Thus aredescribed the structural details of the cam disc 20! and its'manner ofadjustment :for affording "variation in the time duration of -'c'ertainones of itssurface camdepressions. This adjustmentafiords'ameans of'varying the operation interval during which the stoker :S "will run when the contact pair92 is closed'bythe fire pilot timing clock. There "will :now be explained the various details concerning the "cam follower mechanism whichis"carriedupon shaft 253, and iwhihin the'embodiment featured in Figs. 4 to '8 includes two follower :pro'jections 2'63 and 265.

Calling attentiontnow to Fig. 4,1it is to be ob "served that "the small cam disc 235 is divided 'quadrilaterally into four radial cam depressions, ;two of which are designated and 258 at 180 .:'from each other and "the other two of which areibothdesignated 259 at the intervening 180 :from each other. Cam depressions 259 are located at the outermost trackway'on the surface of :disc'235zand'extend"only into a'single zone width towards the center of the disc. Cam depression :258:has approximately twice the width of the cam depressions 259, while cam depression '25! has approximately three times the described width. The :radialextent o'feach of the four cam surfaces :is about the-same,b'eing'roughly and since the cam assembly rotates in a "counter-clockwise direction, each cam recesslis provided with an -as pending slope on its trailing edge so that the Jfollower projection26'5 may ride out of the depressions onto the outer surface of disc 235.

When the follower 265 is disposed in its leftvhand extreme position, as viewed in Fig. 4:, it will ride into and out of all'four of the camrecesses 251, 258 and-the two 259s affording thereby four operations to thecontrol function of stoker drive per hour. When moved rightwardly on shaft 253, the follower assembly will ride into and out of the cam depressions 257 and 258 only, missing the cam depressions 259 and affordingthereby two operations per hour at one-half hour intervals. When the follower is moved to its extreme righthand position projection'265 will ride-into the depression 25! solely, missing the other three zdepressions 2'58 and 255 and affording thereby "but one operation :per hour.

The follower projection 255 is'carried upon an arm 25! of electric insulation material pivoted, as has already been said, on the stud 253. A torsion spring 2520f which two symmetrically opposite ones are provided, imparts counter-clockwise, Fig. 5, rotation to the arm 25!, as well as to the contact extension mounted thereon and carrying the contact point 93.

The principal cam surfaces which are located in disc 20! .are also four in number, all designated 255, each partaking of the same width'and depth in contradistinction from the cam recesses of disc 235, and this depth is sufficient to permit the follower projection 263 to ride in and out of each cam depression throughout the three adjustment positions of the follower assembly made to accommodate the variations of the internal cam disc 235. Accordingly therefore the follower lever 250 operates four times an hour, regardless of the adjustmentand operation of the follower lever 25!. Also it is to be noted that follower lever 250 carries contact point v9! which is maintained in registering alignment with the contact point 93 by virtueof the fact that the two levers 250 and 25! are separated by spacing collars between them on shaft 253 and are constrained against separation by the yoke 254 which is made of sheet metal and which is provided with a manipulation handle 21!.

A number of retaining projections 251, 268 and 269 integrally associated with the case 85 are provided with predetermined spacing between them for the purpose of receiving the manipulation portion 21! and for restraining the yoke 254 thereby against inadvertent longitudinal movement on theshaft 2 53. It is to be noted that the tail ends of the torsion springs 252 which urge the levers 250 and 25! counter-clockwise rest against the yoke 254 urging the latter member clockwise, as viewed in Fig. 5. The effect ofloosening the adjustment screw 244' and of rotating the disc 235 together with its index or pointer 245 relative to the outer cam 20! is to vary the relationship of each cam depression 255 with its associated cam depression 251, 258 or 259, all adjustments being simultaneous. This relative adjustment is translated in terms of radial graduations 24'6 engraved on the surface 2!! of plate 20'! so as to represent minutes of time during each quadrant when the contact pair ill-93 will remain closed. In this way the duration of the operating interval may be regulated between onehalf and seven minutes per quarter. For a greater operating interval of course it is but necessary to provide that the adjustment angle be proportionately wider, which it may be, up to a maximum just short of fifteen minutes. By cutting down the number of operations per hour, this angle may be increased still more as required.

In order for the contact pair'S !--93 to be closed,

I .295 and an inclined rising edge 293.

the follower projection 265 must ride into a surface recession of its cam 235, while the follower projection 263 is held out of itssurface recessions in plate 201, it following from this statement that contact engagement is not had during those intervals when both followers 263 and 265 are riding similar surfaces, that is to say, high spots or low spots in their respective cams.

It is to be observed that in accordance with the structural features of the fire pilot control mechanism thus described, the stoker will be operated at regular intervals when no heat demand signals are transmitted from the room or zone thermostats and that the frequency and duration of these intermittent operations may be regulated by two adjustments, one being on the cam and the other on the follower levers. There will now be described a modified form of pilot control mechanism in which all of the adjustments are carried by the rotary cam device.

Attention will now be directed to Figs. 9 to 14, inclusive. wherein there is featured a modified form of fire pilot control mechanism characterized by the provision of an additional cam surface and follower lever for achieving the objectives of fire piloting. The reference numeral 209, as in the case of the preferred embodiment above, designates a synchronous motor driven hour shaft that is designed to make one complete revolution every sixty minutes. The principal cam designated 280 is in this instance also a disc made of electric insulated material in which is provided asurfaoerecess for nesting the circular disc insert cam 283. An adjustment index 245 carried by a similar triangular plate 222 is also provided, but in addition, a third cam disc indicated 286 is superimposed upon the surface of cam disc 283 and is made angularly adjustable with respect thereto throughout a limited are as afforded by the elongated arcuate slot 28'! and the adjustment screw 289.

As will be observed from Figs. 9 and 10, cam disc 2% .is provided with two surface depressions designated 283', each defined by a drop-off edge The disc cam 283 is provided with four equally spaced peripheral surface depressions designated 308 and the principal disc cam 283 is provided with four identical surface depressions 3!3. The adjustment between disc 283 and the principal cam disc 280 is made in the same manner as in the preferred embodiment, while the adjustment between cam disc 283 and its supporting cam disc 283 requires to be made by manual rotation of disc 283, while the tightening screw 28!! is released. The three follower levers 30!, 3!- and 335 are pivoted on the stud 32! but in this case are confined against longitudinal displacement thereon. Lever 30! has a follower projection designated 33!! for riding in and out of the cam surfaces of disc 286, which it does twice during every revolution at intervals.

Lever 3H1 is provided with a follower projection 33! which rides the surface depressions of disc 283, describing four operations during a cycle while lever 335 having a projection 332 similarly rides in and out of the four cam recesses 3l'3 of disc 286.

At this time it is well to keep in mind that the additional achievement of the modified embodiment is to obtain an interruption in the fuel feeding operation during continuous demand periods of the room or zone thermostats. This condition is achieved by a wiring installation as featured in Fig. 14. It is highly desirable to provide this safeguard because on occasions, due to various characteristics of the fuel and of heating conditions, the residual heat in the fuel bed is suflicient to bring the temperature up to a point where the thermostat circuit will open during the interruption interval. With certain varieties of coal which are less inclined to form clinkers, the practice of frequent interruptions has been found to improve the clinker characteristic, thereby affording an over-all preferred firing performance. Where the fuel feeding device operates continuously throughout the period of thermostat demand, and the furnace temperature is permitted to increase and overrun the heat calling cycle, the clinker characteristic is impaired and ofttimes the room temperature is permitted to rise perceptibly beyond the desired levels.

In view of the cam and follower mechanism already described in Figs. 9 to 14, it will be observed that lever 30l carries a contact arm terminating with the contact point 334, that lever 305 carires a contact arm terminating with the contact point 335 as well as with an additional contact point 339, and that the intermediate lever 3l0 carries an arm having contact point 340. Contact points 334 and 335 are in contactual alignment while contact points 339 and 340 are in contactual alignment. These contact pairs may engage each other when their respective follower projections 330 to 332, inclusive are at variance, that is to say, when one rides an apex and the other a recession in their respective cams.

By referring now to Fig. 14, it will be seen that contact point 334 is connected over a line 302 to the energizing winding 65 of the fire demand call relay whose contact pair 59 controls the operating motor of stoker S and that the opposite terminal of the winding of this relay 65 is connected to the secondary winding 68 of a transformer 10. Also the opposite terminal of transformer winding 68 is connected over a line 304 to the contact points 340 as well as 334. The third contact 339 is connected over a line 3 M, with the contact pair 3l6 of a room thermostat so designed as to close in response to low room temperature, thereby establishing a heat demand.

Accordingly the heat demand period is interrupted by the separation of contact pair 339 and 340. This result will occur when the follower 32 drops into a recess 3l3 while the follower 33! remains out of its recess 308. At all other times the contact pair 339-440 remains closed and permits the heat demand signal to be effective upon the motor of stoker S.

The cooperation between contact pair 335 and 334 is precisely the same as that of contact pair 9| and 93 in the preferred showing of Figs. 4 to 8 inclusive, except that in the particular embodiment only two depressions are provided in cam 286 illustrating an adjustment for foreshortening two of the periodic intervals, it being obvious that all four of the intervals may be correspondingly regulated by providing the appropriate number of recesses 283 in cam 286.

While the present invention has been explained.

discs angularly adjustable each to each and frictionally mounted upon a timed rotary shaft, said discs each having a system of circular cam surfaces on a side face thereof with the side faces of all of said discs being in substantial planar alignment, a plurality of cam disc followers each for one of said discs with all followers mounted on a common pivot, piloting control contacts identified with said followers so as to be opened and closed in accordance with the variations of position assumed by said followers relative to each other, means for varying the timing of said pilot contacts by axially displacing said cam discs in relation to one another, and means for further varying the timing of said piloting contacts by shifting said followers on their common pivot.

2. A sequencing switch for fire piloting operations comprising an assembly of cam discs angularly adjustable each to each, said assembly being frictionally mounted upon a shaft which is rotated at a predetermined rate, said discs each having a system of circular cam surfaces on a side face thereof with the side faces of all of said discs in substantial planar alignment, a plurality of followers each for one of said discs and all mounted on a common pivot, piloting control contacts operated by said followers so as to open and close in accordance with the variations of position assumed by said followers relative to each other, means for varying the periodicity in the timing of said piloting contacts by axially displacing said cam discs in relation to one another, and means for varying the frequency of said timing by shifting said followers on their common pivot.

3. A device for automatically controlling fire pilot operations comprising a plurality of concentric cam discs mounted upon a timed rotary shaft and angularly adjustable each to each, said discs each having a system of circular cam surfaces circumferentially spaced on a side face thereof, a plurality of cam disc followers mounted on a common pivot, piloting control contacts actuated by said followers so as to be opened and closed in accordance with contrasting positions assumed by said followers relative to each other, means for varying the timing of said pilot contacts by axially displacing said cam discs in relation to one another, and means for further varying the timing of said piloting contacts by shifting said followers longitudinally on their common pivot.

4. A sequencing switch for fire piloting operations comprising composited concentric cam discs angularly adjustable each to each and fricticnally driven by a rotary shaft, said discs each having a system of circular cam surfaces on a side face thereof with the side faces of all of said discs being in substantial planar alignment, a cam disc follower for each of said discs and all followers mounted on a common pivot, piloting control contacts identified with said followers so as to be opened and closed in accordance with the variations of position assumed by said followers relative to each other, means for varying the periodicity in the timing of said piloting contacts by axially displacing said cam discs in relation to one another, and means for varying the frequency of said timing by displacing said followers on their common pivot.

5. A sequencin device comprising a plurality of annular cam rings havin related cam surfaces in radial as well as in substantial planar alignment, means for adjusting said rings axially relative to each other and thereby varying the relationship between radially related cam surfaces thereof, a contact controller tracking each of said 1 7 cam rings, a common pivot shaft mounting all of said controllers longitudinally of said shaft for thereby associating said contact controllers with diiferent cam surfaces of said rings.

6. A motor driven sequencing switch for pilotin heat control apparatus comprising a speed regulated rotary power source, a composited cam assembly driven by said source comprised of an outer or primary annular face portion and inner or secondary annular face portions, said face portions being disposed in substantial planar alignment and each having a circular system of cam depressions radially related to cam depressions of a circular system of another of said face portions, means for establishing various angular adjustments between said primary and said secondary face portions, and a plurality of circuit control contact operating members each responsive to a related one of said circular systems of cam depressions for closing and opening heat control circuits during time intervals varying in length according to said angular adjustment between said primary and said secondary face portions.

'7. A sequencing switch for piloting heat control apparatus comprising a speed regulated rotary power source, a cam assembly driven by said source comprised of an outer or primary annular face portion and inner or secondary annular face portions, said outer and inner face portions being disposed in substantial planar alignment and each having a circular system of cam depressions,

means for adjusting said primary and said secondary face portions axially, and a plurality of contact operating members each responsive to a related one of said circular systems of cam depressions for closingand openin heat control circuits for thereby varying the time intervals of heat piloting according to said angular adjustment between said primary and said secondary face portions.

8. In a heat control system, a sequencing device comprising a plurality of annular cam rings having pluralities of cam surfaces in substantial planar alignment, means for adjusting said rings axially relative to each other for thereby varying the relationship between corresponding cam surfaces thereof, a contact lever following the circular path of each of said cam rings, a common pivot shaft mounting all of said contact levers, and means for shifting all of said levers longitudinally of said shaft for thereby associating said contact controllers with different cam surfaces of said rings to affect periodicity variations.

ARTHUR V. SAMPSEL.

REFERENCES CITED UNITED STATES PATENTS Name Date Woodson Oct. 14, 1947 Number 

